Some do, some don't.
The ones that do vary in ability by overall dishwasher quality.
The ones that don't are hooked up to the kitchen's hot water line.
This is considered more energy efficient because a home's hot water heater (whether electric, gas, or another fuel) is better at heating the water in a bulk capacity than a tiny heater in the dishwasher.
The downside is that the cold water between the big water heater and the dishwasher has to be purged first for it to be really effective. If your hot water heater is in the other side of the wall, no problem. If it's six rooms away, problem.